Cell selection and cell re-selection are mechanisms by which wireless devices in a wireless network determine which cell will connect to each wireless device. Initially, a wireless device may detect a reference signal from a cell (i.e. access node). If the reference signal is above a threshold signal level, the wireless device may attempt to connect to this cell by a connection protocol in order to establish communication with the wireless network. Once wireless communication is established, this cell becomes the serving cell for the wireless device. If the serving cell reference signal drops below a threshold, or for other network reasons such as new cell integration, maintenance, or monitoring, the wireless device may be triggered to begin a process for cell re-selection.
Cell re-selection may include measurement by the wireless device of signal levels and network characteristics for all detected cells. The wireless device or another network node may report these measurements to the serving cell for use during the handover process. When cells should not be re-selected for handover, it is known to “blacklist” those cells in the memory of a serving cell. It may be desirable to determine and update information regarding suitable candidates for handover of wireless devices due to the signal levels and the network characteristics of these cells. It may further be desirable to continue monitoring cells included in the “blacklist” and to remove them from the “blacklist” when one or both of the signal levels and network characteristics improve above threshold values.
Overview
Systems and methods are described for determining candidate access nodes for handover of wireless devices having various classifications. A first access node may receive signal information for one or more second access nodes from a plurality of wireless devices in wireless communication with the first access node. A communication link established between the first access node and each of the second access nodes may be used to provide information and updates from the second access nodes to the first access node regarding network characteristics of each of the second access nodes. A first access node neighbor relation table (NRT) removal condition may be calculated for each of the second access nodes based on the received second access node signal information and the received second access node network characteristics. Second access nodes for which the removal condition is satisfied may be removed from the first access node NRT, and may be added to a blacklist, whereupon blacklisted second access nodes may not be added back to the first access node NRT by a protocol such as an automatic neighbor relation (ANR) process. Blacklisted second access nodes may periodically monitored for any changes in signal information or network characteristics, and second access nodes having improved signal information or network characteristics may be added back to the first access node NRT so that they may be candidates for handover of wireless devices.